Thirty-one Japanese bombs, with seven confirmed to be chemical weapons, were recovered on Wednesday in Ning'an City, northeast China's Heilongjiang Province.

Huang Shunxiang, digs out a bomb at an excavation site of World War Two chemical weapons abandoned by Japan, in Ning'an, China's Heilongjiang province, July 5, 2006. The joint Chinese-Japanese team was preparing Wednesday to excavate abandoned Japanese poison gas bombs from World War II that were buried near a school after a factory received them as scrap metal. [Reuters]

Experts from Japan and China began on Wednesday excavating a pit at the Ning'an Chemical and Light Industry Company where they expected to recover more than 200 bombs that were abandoned by Japanese troops at the end of World War II.

Wang Xuefeng, a Chinese official on the recovery team, estimated 100 of the bombs might be armed with deadly chemicals.

Over the course of eight days of excavation, 20 Japanese experts, assisted by their Chinese counterparts, will confirm the status of the weapons and pack them for safe keeping.

The Chinese Foreign Ministry said Japan abandoned at least 2 million tons of chemical weapons in China. More than 2,000 Chinese people have been killed by abandoned chemical weapons since the war ended in 1945.

Liu Yiren, who heads an office in charge of abandoned weapons at the Chinese Foreign Ministry, said China has so far retrieved and disposed of nearly 40,000 chemical weapons. "However, it is only the tip of an iceberg," he said.

A lack of information from Japan about where they abandoned or buried their weapons has made it difficult to track and account for them.

The two countries have conducted more than 60 courses on the safe recovery of the weapons, said Liu.

While the experts have packed the weapons to make them safe, Liu said, none of them have been destroyed as they are extremely dangerous and a safe disposal plant will soon be built.